Cephalopods may be Spreading due to Climate Change

Humans have changed the world's oceans in ways that have been devastating to many marine species. But, according to new evidence, it appears that the change has so far been good for cephalopods, the group including octopuses, cuttlefish, and squid. The study reported in the Cell Press journal Current Biology on May 23 shows that cephalopods' numbers have increased significantly over the last six decades.

"The consistency was the biggest surprise," says Zoë Doubleday of Australia's Environment Institute at the University of Adelaide. "Cephalopods are notoriously variable, and population abundance can fluctuate wildly, both within and among species. The fact that we observed consistent, long-term increases in three diverse groups of cephalopods, which inhabit everything from rock pools to open oceans, is remarkable."

According to the researchers, there has been growing speculation that cephalopod populations were proliferating in response to a changing environment, based partly on trends in cephalopod fisheries. Cephalopods are known for rapid growth, short lifespans, and extra-sensitive physiologies, which may allow them to adapt more quickly than many other marine species.

link.

Symbiosis Between Lobsters and Bivalves During the Aptian Cretaceous

Bivalves on mecochirid lobsters from the Aptian of the Isle of Wight: Snapshot on an Early Cretaceous palaeosymbiosis

Authors:

Robin et al

Abstract:

Fossil symbioses (Bary 1879) that are not recognized in modern assemblages are rare. This holds true especially because fossil remains of interspecific association are sporadic and difficult to document. Thus, fossil associations illustrated on a large number of specimens are of particular interest. Numerous specimens of mecochirid lobsters (Glypheidea, Decapoda, Crustacea) from the Lower Cretaceous of the Atherfield Clay Formation (Isle of Wight, UK) seer small epibiotic bivalves on their exoskeleton. We propose to identify the post-mortem or syn-vivo nature of this association. To this end, we test and revise the systematic assignment of both crustacean and molluscan partners. A new genus name is proposed for the crustacean Meyeria magna M'Coy, 1849, as well as the new combination Atherfieldastacus magnus (M'Coy, 1849). To understand the nature of the association, a qualitative and quantitative study of the association is conducted on newly examined material (161 lobsters) looking at prevalence, density and abundance of the infestation (per anatomical region of the lobsters). Angularities and flat surface of exoskeletons were also evaluated. The distribution of the bivalves on both sides of the crustaceans (60% of the colonized lobsters), their preservation and their downward growth orientation suggests no post-mortem attachment of the mollusks. Hence, the association may be ascribed to a true palaeosymbiosis between these organisms. The non-homogeneous distribution of bivalves, that is to say an important colonization of the angular ridges of the carapace, is interpreted as selected sites by the mollusks for larval fixation, and may indicate possible half-burrowing posture of lobsters. This palaeosymbiosis has no modern equivalent, as cemented bivalve shells have never been reported on any population of decapod crustaceans. This fossil association may be ascribed to a local Aptian palaeoenvironment comprising swarming spats of anomiid bivalves.

Giant Squid Surfaces off Coast of Japan, Tokyo Surprisingly NOT Destroyed

Elysia chlorotica: Meet the Photosynthetic Sea Slug

How a brilliant-green sea slug manages to live for months at a time "feeding" on sunlight, like a plant, is clarified in a recent study published in The Biological Bulletin.

The authors present the first direct evidence that the emerald green sea slug's chromosomes have some genes that come from the algae it eats.

These genes help sustain photosynthetic processes inside the slug that provide it with all the food it needs.

Importantly, this is one of the only known examples of functional gene transfer from one multicellular species to another, which is the goal of gene therapy to correct genetically based diseases in humans.

"Is a sea slug a good [biological model] for a human therapy? Probably not. But figuring out the mechanism of this naturally occurring gene transfer could be extremely instructive for future medical applications," says study co-author Sidney K. Pierce, an emeritus professor at University of South Florida and at University of Maryland, College Park.

The team used an advanced imaging technique to confirm that a gene from the alga V. litorea is present on the E. chlorotica slug's chromosome. This gene makes an enzyme that is critical to the function of photosynthetic "machines" called chloroplasts, which are typically found in plants and algae.

It has been known since the 1970s that E. chloritica "steals" chloroplasts from V. litorea (called "kleptoplasty") and embeds them into its own digestive cells. Once inside the slug cells, the chloroplasts continue to photosynthesize for up to nine months--much longer than they would perform in the algae. The photosynthesis process produces carbohydrates and lipids, which nourish the slug.

How the slug manages to maintain these photosynthesizing organelles for so long has been the topic of intensive study and a good deal of controversy. "This paper confirms that one of several algal genes needed to repair damage to chloroplasts, and keep them functioning, is present on the slug chromosome," Pierce says. "The gene is incorporated into the slug chromosome and transmitted to the next generation of slugs." While the next generation must take up chloroplasts anew from algae, the genes to maintain the chloroplasts are already present in the slug genome, Pierce says.

link.

Mollusc Origins Traced to Ediacaran Fossil Kimberella

The origins of molluscs

Author:

Vinther

Abstract:

The interrelationships and evolutionary history of molluscs have seen great advances in the last decade. Recent phylogenetic studies have allowed alternative morphology-based evolutionary scenarios to be tested and, most significantly, shown that the aplacophorans are sister group to polyplacophorans (chitons), corroborating palaeontological and embryological evolutionary scenarios in which aplacophorans are secondarily simplified from a chiton-like ancestor. Aplacophoran morphology therefore does not represent the plesiomorphic condition for molluscs as a whole. The mollusc crown group radiated in the Early Cambrian, and rapidly thereafter, stem lineages to the major molluscan classes emerged: cephalopods, gastropods, bivalves (= pelecypods), monoplacophorans, rostroconchs (inferred stem scaphopods) and aculiferans. This attests to the fast, adaptive radiation of the crown group during the Cambrian explosion. Kimberella from the latest Ediacaran exhibits several molluscan traits, which justifies its position as a molluscan stem-group member, rather than as a more basal Lophotrochozoan. The interrelationships among the conchiferan molluscs are still a matter of contention and require further palaeontological and molecular phylogenetic scrutiny.

A Social Octopus Found

If recent octopus discoveries have taught us anything, it's that these eight-armed ocean dwellers are smart. They can use tools, change color in an instant, and commission their arms to solve problems. But they generally do all this as loners.

Now, new research into a surprisingly social octopus is shattering even the most expansive ideas of known octopus behavior.

Panamanian biologist Aradio Rodaniche first reported the Pacific striped octopus in 1991 off the coast of Nicaragua, noting its strange behavior—living in groups of possibly up to 40, laying multiple egg clutches, and mating face-to-face and sucker-to-sucker. Most other octopus species, for instance, come together only to mate.

But scientists didn't see another one of these curious octopuses for another 20 years, when Richard Ross, a biologist at the California Academy of Sciences, came across one in 2012. Through a commercial collector, he acquired several wild specimens to study in the lab.

Ross is one of the few scientists who are studying and observing some of this octopus's truly bizarre—and sometimes anxiety-provoking—behavior, which he and his team will describe in an upcoming publication.

"Regular octopus mating, where the male is behind and on top of the [female]—or far away—that's scary enough to watch," said Ross. Females of many species, for instance, will sometimes kill and eat their mate, even if they are mating from a distance.

But "watching these guys come and interact with their beaks—wrapped up in a ball of limbs—are they fighting or mating?" he recalled wondering.

link.

How Marine Molluscs Recovered From the KT/K-Pg Mass Extinction in Patagonia

Rebuilding Biodiversity of Patagonian Marine Molluscs after the End-Cretaceous Mass Extinction

Authors:

Aberhan et al

Abstract:

We analysed field-collected quantitative data of benthic marine molluscs across the Cretaceous–Palaeogene boundary in Patagonia to identify patterns and processes of biodiversity reconstruction after the end-Cretaceous mass extinction. We contrast diversity dynamics from nearshore environments with those from offshore environments. In both settings, Early Palaeogene (Danian) assemblages are strongly dominated by surviving lineages, many of which changed their relative abundance from being rare before the extinction event to becoming the new dominant forms. Only a few of the species in the Danian assemblages were newly evolved. In offshore environments, however, two newly evolved Danian bivalve species attained ecological dominance by replacing two ecologically equivalent species that disappeared at the end of the Cretaceous. In both settings, the total number of Danian genera at a locality remained below the total number of late Cretaceous (Maastrichtian) genera at that locality. We suggest that biotic interactions, in particular incumbency effects, suppressed post-extinction diversity and prevented the compensation of diversity loss by originating and invading taxa. Contrary to the total number of genera at localities, diversity at the level of individual fossiliferous horizons before and after the boundary is indistinguishable in offshore environments. This indicates an evolutionary rapid rebound to pre-extinction values within less than ca 0.5 million years. In nearshore environments, by contrast, diversity of fossiliferous horizons was reduced in the Danian, and this lowered diversity lasted for the entire studied post-extinction interval. In this heterogeneous environment, low connectivity among populations may have retarded the recolonisation of nearshore habitats by survivors.

Trace Fossils Tied to Mollusc-like Bilateral Animals From the Ediacaran NeoProterozoic

Scratch Traces of Large Ediacara Bilaterian Animals

Authors:

Gehling et al

Abstract:

Ediacara fan-shaped sets of paired scratches Kimberichnus teruzzii from the Ediacara Member of the Rawnsley Quartzite, South Australia, and the White Sea region of Russia, represent the earliest known evidence in the fossil record of feeding traces associated with the responsible bilaterian organism. These feeding patterns exclude arthropod makers and point to the systematic feeding excavation of seafloor microbial mats by large bilaterians of molluscan grade. Since the scratch traces were made into microbial mats, animals could crawl over previous traces without disturbing them. The trace maker is identified as Kimberella quadrata, whose death masks co-occur with the mat excavation traces in both Russia and South Australia. The co-occurrence of animals and their systematic feeding traces in the record of the Ediacara biota supports previous trace fossil evidence that bilaterians existed globally before the Cambrian explosion of life in the ocean.

Native Americans in British Columbia Practiced Aquaculture Through Clam Gardens

Ancient Clam Gardens Increased Shellfish Production: Adaptive Strategies from the Past Can Inform Food Security Today

Authors:

Groesbeck et al

Abstract:

Maintaining food production while sustaining productive ecosystems is among the central challenges of our time, yet, it has been for millennia. Ancient clam gardens, intertidal rock-walled terraces constructed by humans during the late Holocene, are thought to have improved the growing conditions for clams. We tested this hypothesis by comparing the beach slope, intertidal height, and biomass and density of bivalves at replicate clam garden and non-walled clam beaches in British Columbia, Canada. We also quantified the variation in growth and survival rates of littleneck clams (Leukoma staminea) we experimentally transplanted across these two beach types. We found that clam gardens had significantly shallower slopes than non-walled beaches and greater densities of L. staminea and Saxidomus giganteus, particularly at smaller size classes. Overall, clam gardens contained 4 times as many butter clams and over twice as many littleneck clams relative to non-walled beaches. As predicted, this relationship varied as a function of intertidal height, whereby clam density and biomass tended to be greater in clam gardens compared to non-walled beaches at relatively higher intertidal heights. Transplanted juvenile L. staminea grew 1.7 times faster and smaller size classes were more likely to survive in clam gardens than non-walled beaches, specifically at the top and bottom of beaches. Consequently, we provide strong evidence that ancient clam gardens likely increased clam productivity by altering the slope of soft-sediment beaches, expanding optimal intertidal clam habitat, thereby enhancing growing conditions for clams. These results reveal how ancient shellfish aquaculture practices may have supported food security strategies in the past and provide insight into tools for the conservation, management, and governance of intertidal seascapes today.

A New Approach for the Determination of Ammonite and Nautilid Habitats

A New Approach for the Determination of Ammonite and Nautilid Habitats

Authors:

Cruta et al

Abstract:

Externally shelled cephalopods were important elements in open marine habitats throughout Earth history. Paleotemperatures calculated on the basis of the oxygen isotope composition of their shells can provide insights into ancient marine systems as well as the ecology of this important group of organisms. In some sedimentary deposits, however, the aragonitic shell of the ammonite or nautilid is poorly or not preserved at all, while the calcitic structures belonging to the jaws are present. This study tests for the first time if the calcitic jaw structures in fossil cephalopods can be used as a proxy for paleotemperature. We first analyzed the calcitic structures on the jaws of Recent Nautilus and compared the calculated temperatures of precipitation with those from the aragonitic shell in the same individuals. Our results indicate that the jaws of Recent Nautilus are secreted in isotopic equilibrium, and the calculated temperatures approximately match those of the shell. We then extended our study to ammonites from the Upper Cretaceous (Campanian) Pierre Shale of the U.S. Western Interior and the age-equivalent Mooreville Chalk of the Gulf Coastal Plain. In the Pierre Shale, jaws occur in situ inside the body chambers of well-preserved Baculites while in the Mooreville Chalk, the jaw elements appear as isolated occurrences in the sediment and the aragonitic shell material is not preserved. For the Pierre Shale specimens, the calculated temperatures of well-preserved jaw material match those of well-preserved shell material in the same individual. Analyses of the jaw elements in the Mooreville Chalk permit a comparison of the paleotemperatures between the two sites, and show that the Western Interior is warmer than the Gulf Coast at that time. In summary, our data indicate that the calcitic jaw elements of cephalopods can provide a reliable geochemical archive of the habitat of fossil forms.

Mollusc vs Vertebrate War: Battle in the Monterey Bay

nice pop sci write up at the Running Ponies about the squid.

Ireland Invaved by French Snails...8,000 Years Ago

Some snails in Ireland and the Pyrenees are genetically almost identical, perhaps because they were carried across the Atlantic during an 8000-year-old human migration. The snail genetics tie in with studies of human genetics and the colonization of Ireland, according to the research published June 19 in the open access journal PLOS ONE by Angus Davison and colleagues from the University of Nottingham, UK.

Despite being thousands of miles apart, one variety of banded wood snails from Ireland and southern France share similar shell patterns and mitochondrial genes that are rarely seen in other areas of Europe. Davison explains, "There is a very clear pattern, which is difficult to explain except by involving humans. If the snails naturally colonized Ireland, you would expect to find some of the same genetic type in other areas of Europe, especially Britain. We just don't find them."

He adds, "There are records of Mesolithic or Stone Age humans eating snails in the Pyrenees, and perhaps even farming them. The highways of the past were rivers and the ocean – as the river that flanks the Pyrenees was an ancient trade route to the Atlantic, what we're actually seeing might be the long lasting legacy of snails that hitched a ride, accidentally or perhaps as food, as humans travelled from the South of France to Ireland 8,000 years ago."

Out of Tropics: Species Originate in Tropics and Spread

Although scientists have known since the middle of the 19th century that the tropics are teeming with species while the poles harbor relatively few, the origin of the most dramatic and pervasive biodiversity on Earth has never been clear.

New research sheds light on how that pattern came about. Furthermore, it confirms that the tropics have been and continue to be the Earth's engine of biodiversity.

By examining marine bivalves (two-shelled mollusks including scallops, cockles and oysters), a model system for large-scale ecological and evolutionary analysis, the study shows that most evolutionary lineages started in the tropics and expanded outward.

"This 'out of the tropics' dynamic is the major process that shapes the latitudinal pattern of biodiversity that we see today on land and sea," said lead author David Jablonski, the William R. Kenan Jr. Professor in Geophysical Sciences at the University of Chicago. His team focuses on marine bivalves because they combine a wealth of important biological patterns with a large but manageable number of living species (about 8,000) and a rich fossil record.

The new research will be published this week in the online Early Edition of the Proceedings of the National Academy of Sciences presents evidence that the "out of the tropics" process is driven mainly by bridge species, a new term referring to evolutionary lineages that straddle the boundary between the tropics and cooler neighboring regions.

"We thought the 'out of the tropics' process would be driven by the formation of new species at the edge of the tropics, but that doesn't seem to be true," Jablonski said. "Whether bridge species really are the conduit, 'out of the tropics' for all those lineages still needs to be confirmed. We'll tackle that next, by examining molecular data on species within these lineages, inside and outside the tropics, to see how they're related."

As with the PNAS study, this follow-up research would require examining data on both fossils and living organisms. "Alas, it's still rare for paleontologists to integrate the fossil record with data on present-day organisms, but for large-scale biodiversity studies like this, it's a very powerful approach, often an essential one," Jablonski said. "Biodiversity is a product of origination, extinction and immigration, and when the fossil record is adequate, as it is with bivalves, it provides the most robust window into the dynamics that produced present-day patterns."

Tropical Species Impacted Worse During KT/K-Pg Extinction

Bivalve network reveals latitudinal selectivity gradient at the end-Cretaceous mass extinction

Authors:

1. Daril A. Vilhena (a)
2. Elisha B. Harris (a,b)
3. Carl T. Bergstrom (a,c)
4. Max E. Maliska (a)
5. Peter D. Ward (a,b,d)
6. Christian A. Sidor (a,b)
7. Caroline A. E. Strömberg (a,b)
8. Gregory P. Wilson (a,b)

Affiliations:

a. Department of Biology, University of Washington, Seattle, WA 98195-1800

b. Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195-3010

c. Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM 87501

d. Department of Earth and Space Science, University of Washington, Seattle, WA 98195-1800

Abstract:

Biogeographic patterns of survival help constrain the causal factors responsible for mass extinction. To test whether biogeography influenced end-Cretaceous (K-Pg) extinction patterns, we used a network approach to delimit biogeographic units (BUs) above the species level in a global Maastrichtian database of 329 bivalve genera. Geographic range is thought to buffer taxa from extinction, but the number of BUs a taxon occurred in superseded geographic range as an extinction predictor. Geographically, we found a latitudinal selectivity gradient for geographic range in the K-Pg, such that higher latitude BUs had lower extinction than expected given the geographic ranges of the genera, implying that (i) high latitude BUs were more resistant to extinction, (ii) the intensity of the K-Pg kill mechanism declined with distance from the tropics, or (iii) both. Our results highlight the importance of macroecological structure in constraining causal mechanisms of extinction and estimating extinction risk of taxa.

Molluscan Tool Use

Scientists once thought of tool use as a defining feature of humans. That's until examples of tool use came in from other primates, along with birds and an array of other mammals. Now, a report in the December 14th issue of Current Biology, a Cell Press publication, adds an octopus to the growing list of tool users.

The veined octopus under study manages a behavioral trick that the researchers call stilt walking. In it, the soft-bodied octopus spreads itself over stacked, upright coconut shell "bowls," makes its eight arms rigid, and raises the whole assembly to amble on eight "stilts" across the seafloor. The only benefit to the octopus's ungainly maneuver is to use the shells later as a shelter or lair, and that's what makes it wholly different from a hermit crab using the discarded shell of a snail.

"There is a fundamental difference between picking up a nearby object and putting it over your head as protection versus collecting, arranging, transporting (awkwardly), and assembling portable armor as required," said Mark Norman of the Museum Victoria in Australia.

Julian Finn, also of the Museum Victoria, said the initial discovery was completely serendipitous.

"While I have observed and videoed octopuses hiding in shells many times, I never expected to find an octopus that stacks multiple coconut shells and jogs across the seafloor carrying them," he said.

In recalling the first time that he saw this behavior, Finn added, "I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away. It was an extremely comical sight—I have never laughed so hard underwater."

Wooow.

Many Shelled Animals Respond Unexpectedly to Raised Carbon Dioxide Levels

In a striking finding that raises new questions about carbon dioxide's (CO2) impact on marine life, Woods Hole Oceanographic Institution (WHOI) scientists report that some shell-building creatures—such as crabs, shrimp and lobsters—unexpectedly build more shell when exposed to ocean acidification caused by elevated levels of atmospheric carbon dioxide (CO2).

Because excess CO2 dissolves in the ocean—causing it to "acidify" —researchers have been concerned about the ability of certain organisms to maintain the strength of their shells. Carbon dioxide is known to trigger a process that reduces the abundance of carbonate ions in seawater—one of the primary materials that marine organisms use to build their calcium carbonate shells and skeletons.

The concern is that this process will trigger a weakening and decline in the shells of some species and, in the long term, upset the balance of the ocean ecosystem.

But in a study published in the Dec. 1 issue of Geology, a team led by former WHOI postdoctoral researcher Justin B. Ries found that seven of the 18 shelled species they observed actually built more shell when exposed to varying levels of increased acidification. This may be because the total amount of dissolved inorganic carbon available to them is actually increased when the ocean becomes more acidic, even though the concentration of carbonate ions is decreased.

"Most likely the organisms that responded positively were somehow able to manipulate…dissolved inorganic carbon in the fluid from which they precipitated their skeleton in a way that was beneficial to them," said Ries, now an assistant professor in marine sciences at the University of North Carolina. "They were somehow able to manipulate CO2…to build their skeletons."

Organisms displaying such improvement also included calcifying red and green algae, limpets and temperate urchins. Mussels showed no effect.

"We were surprised that some organisms didn't behave in the way we expected under elevated CO2," said Anne L. Cohen, a research specialist at WHOI and one of the study's co-authors. "What was really interesting was that some of the creatures, the coral, the hard clam and the lobster, for example, didn't seem to care about CO2 until it was higher than about 1,000 parts per million [ppm]." Current atmospheric CO2 levels are about 380 ppm, she said. Above this level, calcification was reduced in the coral and the hard clam, but elevated in the lobster

The "take-home message, " says Cohen, is that "we can't assume that elevated CO2 causes a proportionate decline in calcification of all calcifying organisms." WHOI and the National Science Foundation funded the work.

Conversely, some organisms—such as the soft clam and the oyster—showed a clear reduction in calcification in proportion to increases in CO2. In the most extreme finding, Ries, Cohen and WHOI Associate Scientist Daniel C. McCorkle exposed creatures to CO2 levels more than seven times the current level.

This led to the dissolving of aragonite—the form of calcium carbonate produced by corals and some other marine calcifiers. Under such exposure, hard and soft clams, conchs, periwinkles, whelks and tropical urchins began to lose their shells. "If this dissolution process continued for sufficient time, then these organisms could lose their shell completely," he said, "rendering them defenseless to predators."

"Some organisms were very sensitive," Cohen said, "some that have commercial value. But there were a couple that didn't respond to CO2 or didn't respond till it was sky-high—about 2,800 parts per million. We're not expecting to see that [CO2 level] anytime soon."

The researchers caution, however, that the findings—and acidification's overall impact—may be more complex than it appears. For example, Cohen says that available food and nutrients such as nitrates, phosphates and iron may help dictate how some organisms respond to carbon dioxide.

"We know that nutrients can be very important," she says. "We have found that corals for example, that have plenty of food and nutrients can be less sensitive" to CO2. "In this study, the organisms were well fed and we didn't constrain the nutrient levels.

"I wouldn't make any predictions based on these results. What these results indicate to us is that the organism response to elevated CO2 levels is complex and we now need to go back and study each organism in detail."

Let me second the endorsement of the idea that more study needs to be done.

However, based on past levels of CO2 content in the atmosphere, in Deep Time such as the Eocene, that all shelly animals would get whacked seemed...a little more apocalyptic than based in reality. To me. However, those were generally different species and genera than what's here now. But on the other hand, that the idea that all shelled mollusks, etc. would disappear seemed rather unlikely.

Bivalve Fossil Census Hints Origination Rates Higher

Paleontologists can still hear the echo of the death knell that drove the dinosaurs and many other organisms to extinction following an asteroid collision at the end of the Cretaceous Period 65 million years ago.

"The evolutionary legacy of the end-Cretaceous extinction is very much with us. In fact, it can be seen in virtually every marine community, every lagoon, every continental shelf in the world," said University of Chicago paleontologist David Jablonski. It is, he said, "sort of an echo of the big bang for evolutionary biology."

This conclusion followed a detailed global analysis of marine bivalves, one of the few groups plentiful enough in the fossil record to allow such a study, which was funded by the National Aeronautics and Space Administration. Andrew Krug of the University of Chicago, Jablonski and James Valentine of the University of California, Berkeley, examined the geologic ages of every major lineage of living bivalves the world over, from oysters and scallops to quahogs and cockles. Their report appears in the Feb. 6 issue of the journal Science.

The team followed procedures similar to taking a census of everyone living in Chicago, inferring birth rates from that age profile, and then comparing them to a census for Tokyo, Mexico City and other major international metropolitan areas.

Their analysis quantified the time of origin for 711 lineages of bivalves living in the oceans today, and converted them to evolutionary origination rates. In all but the highest-latitude locations, the team saw the clear signs of a strong increase in origination rates following the end of the Cretaceous.

That was no great surprise, Jablonski said, because "the post-extinction recovery pulse is dramatic—we've known about it for a long time." The surprising finding was that the initial 10 million-year boom never really went bust. The origination rate slowed a bit, but did not drop back to the levels that preceded the mass extinction. "It was as if the post-war baby boom birth rate slowed slightly but never returned to pre-war levels," he said.

Why the origination rate failed to drop to previous levels remains an unsolved question, "one that we never even would have asked if we hadn't analyzed the data in this new way," Jablonski noted. "It could be that the extinction took out competitors that had been holding the bivalves back, and permanently opened more room to diversify. Or the post-extinction increase in predation by crabs, fish and other enemies may have spurred the bivalves to keep evolving at a faster pace." These will be interesting ideas to test next, according to Jablonski.

Huh. I wonder if that will hold up for vertebrates (if it does for bivalves). It could mean that we haven't yet hit stable state for our ecology even prior to the current Sixth Mass Extinction. It's an interesting thought.

Then...OMG, we're in the middle of the Late Ceno-Triassic Mass Extinction! AAAAAAAAAAAAAAAAH!!!!

Squids With...Elbows?!

What the...

Link above has more and a video of the weird-o.

Whoa: Pyrite Armour Footed Snails

Hat Tip to Doug.

WOW!

Inspired By James: The Flamboyant Cuttlefish

We watched Nova's presentation on the Cuttlefish the other day. When we saw the Flamboyant Cuttlefish's segment, there was an off-hand comment that based on the fact that these things are terrible swimmers, but good, if poisonous, walkers that someday they might evolve to the point where they move onto land. This has been posited a few times by various future evolution types. The fact that anything FC derived came onto land and the poison aspect was preserved it'd be a damned hard thing to stop them coming out and saying 'hi'.